1. Field of the Invention
This invention relates to the separation of cereal hydrocolloidal compositions from the crude fiber components of oat, barley, or combinations of grain products. The cereal hydrocolloidal compositions are useful as texturizers and nutrients for improving the health benefits of foods.
Dietary fibers are the soluble and insoluble components of cell walls that are resistant to endogenous digestion in the human upper digestive tract [Am. J. Clin. Nutr. 25: 464-465 (1972)]. Such fibers consist primarily of cellulose, hemicellulose, pectic substances, oligosaccharides, lignin, gums and mucilages.
Dietary fiber has been an important food component since early times. Diets containing significant amounts of dietary fiber are known to assist in the digestive process. Burkitt et al. [Lancet 2: 1408-1411 (1972)] teach that dietary fiber has a role in the prevention of certain large-intestine diseases, including cancer of the colon and diverticulitis. Burkitt et al. also indicate that serum cholesterol rises when dietary fiber is removed from the diet, and that eating a fiber-rich diet lowers serum cholesterol. Trowell [Am. J. Clin. Nutr. 25: 464-465 (1972)] and Dreher [Handbook of Dietary Fiber, An Applied Approach, Marcel Dekker, Inc., New York, N.Y. (1987)] have reported on similar conclusions regarding the relationship between fiber and health benefits.
It is now known that soluble and insoluble fibers provide different health benefits. For example, wheat bran is very rich in insoluble crude fiber (mainly cellulose and hemicelluloses) and is excellent for decreasing the transit time of food through the digestive tract [Anderson et al., Am. J. Clin. Nutr. 32: 346-363 (1979)]. Some soluble fibers, especially beta-glucan, are reported to reduce total plasma cholesterol [Behall et al., J. Am. Coll. Nutr. 16: 46-51 (1997)].
2. Description of the Prior Art
Dietary fiber typically consists of morphologically intact cellular tissues of various seed brans, hulls, and other agricultural by-products that have a high content of crude fiber [Dintzis et al., Cereal Chem. 56:123-127 (1979)]. When added to foods, these fibers impart a gritty texture to the final product. One solution to this problem has been to grind the fibers to give finer powders, but these powders still retain their high crude fiber contents. Likewise, the alkaline or alkaline/peroxide treatment of agricultural byproducts as reported by Gould (U.S. Pat. Nos. 4,649,113 and 4,806,475), Gould et al. (U.S. Pat. No. 4,774,098), Ramaswamy (U.S. Pat. No. 5,023,103); and Antrim (U.S. Pat. No. 4,038,481) does not remove the crude fiber. Morley et al. (U.S. Pat. No. 4,565,702) and Sharma (U.S. Pat. No. 4,619,831) teach enrobing the high crude fiber insoluble dietary fibers with soluble fibers (gums) for providing better texture and mouthfeel.
Soluble fibers are water-soluble polysaccharides such as pectin-like fruit and beet by-products (Thibault et al., U.S. Pat. No. 5,275,834). There have been a number of reports of alkaline extraction of agricultural materials, including hulls and brans, for obtaining their soluble hemicellulose components (Wolf, U.S. Pat. No. 2,709,699; Rutenberg et al., U.S. Pat. No. 2,801,955; and Gerrish et al., U.S. Pat. No. 3,879,373).
Gould et al., U.S. Pat. No. 4,497,840, describe foods made from oat bran which contain at least 150% more crude fiber than the whole oat flour. Also, Murtaugh et al., U.S. Pat. No. 4,908,223, show grinding oat bran and rice products to make frozen desserts without any separation of crude fiber components. Rudel, U.S. Pat. No. 4,961,937, also used non-separated oat products in baked products.
The oat soluble fiber, also called oat gum or beta-glucan, of the oat groat was fractionated as a separate component by an extensive series of separation described by Hohner and Hyldon, U.S. Pat. No. 4,028,468. Another wet-milling of oats to give various fractions including oat proteins was described by Cluskey et al., Cereal Chem., 50, 475(1973). Also beta-glucan enriched cellulose-containing fiber with little starch was described by Lehtomaki et al., U.S. Pat. No. 5,183,677. Oat beta-glucan was water extracted from oat groat in U.S. Pat. No. 5,512,287 by Wang et al. Also, barley beta-glucan was purified by an alkaline extraction procedure of Bhatty (U.S. Pat. No. 5,518,710).
Inglett (U.S. Pat. No. 4,996,063) teaches that water-soluble dietary fiber compositions are prepared by treatment of milled oat products with .alpha.-amylase and removal of insoluble components by centrifugation. In a related development, Inglett (U.S. Pat. No. 5,082,673) teaches that a soluble dietary fiber and maltodextrin-containing product is prepared by hydrolyzing a cereal flour or a blend of cereal flour and starch with an .alpha.-amylase. This soluble fiber composition has been described for use in ready-to-eat cereal (Smith and Meschewski, U.S. Pat. No. 5,275,831) and low fat comminuted meat products (Jenkins and Wild, U.S. Pat. Nos. 5,294,457 and 5,585,131).
The use of mechanical shear to reduce the viscosity of cereal flours has been described by Gantwerker and Leong, U.S. Pat. Nos. 4,438,150 and 4,485,120, to prepare instant cereal porridges. There is no teaching or suggestion in these patents that involve separating any component of the cooked flours.